Salesforce have started to announce some details of what we can expect in Winter 18... One thing to change is the look and feel of Lightning Experience.
While the current look is considerably more modern than classic Salesforce, it is pretty overwhelmingly white. In Winter 18, we will see some colour underneath that, and something which is a bit easier on the eye.
Beyond this obvious change, we can also expect various font tweaks, improving clarity and also getting more information onto your screen.
Looking forward to seeing improvements land for our Lightning customers with little/no effort!
The new background image and color helps eliminate the feeling of “snow blindness” that many users felt